Ecology, Environmental Heterogeneity, Aquatic Environment, Terrestrial Environment, Genetics Review, Plant Adaptations, Animal Adaptations

Ecology

Scientific study of interactions between organisms and environment

-> derived from Greek term 'oikos' meaning 'home'

Organism

Living thing

Environment

All factors outside organism that influence it

-> There are two environmental factors

Environment: Abiotic Factors

Physical and chemical factors in the environment (non-living aspects of the environment)

Environment: Biotic factors

Other organisms in the environment (living aspects of the environment)

What is the goal of Ecology?

Ecology can help us explain/understand ecological processes and answer questions such as:

- How do abiotic and biotic factors influence the distribution and abundance of organisms?

- Where are the organisms found?

- How many organisms are there?

- What do organisms do?

- In this course we are mostly interested in the process of birth, death and migration.

What are the two classes of explanation that are used to explain how abiotic and biotic environmental factors influence an organism?

Proximal: Patterns explained by present/current environment.

Ex. How did the weather (rain) this summer influence plant growth in the region?

Ultimate: Patterns explained by the past environment (i.e ecological experiences of ancestors through evolution)

Ex. How has the climate over the past 1000 years influence the plant species present in the region?

Explain what the Scientific Method is and Provide an example using Ecology.

Ecology is a science that is rooted in many scientific disciplines. When conducting an ecological study, scientists must use the Scientific Method in order to determine whether their hypothesis is right or wrong.

-> A Hypothesis is a prediction that can be replicated and tested.

List and Explain what the Ecology Hierarchy is.

Individual: at the most basic level of the Hiearchy are individual organisms.

Populations: the next level are members of the same species which forms populations within a location

Community: populations of different species interact among themselves to form a community.

Define Climate and Weather and include which of the two Evironmental Explanations they fall under.

Climate: a long term average pattern of weather on a local, regional or global scale. Climate would fall under the Ultimate explanation (patterns explained by the past environment)

Weather: is the combination of temperature, humidity, precipitation, wind, cloudiness, etc, at a specific place and time. This would make Weather fall under the Proximal explanation (patterns explained by the current/present environmental conditions.)

What is Solar Radiation and why is it important?

Solar Radiation is main source of energy, absorbed by earth's surface.

All of the differences in climate across the earth are driven primarily by solar radiation.

The ability to sustain life on our planet is due to the sun. Furthermore it is the main source of energy and the absorbed energy can be re-emitted as heat.

-> Only 51% of solar energy reaches the surface of the earth and is absorbed, the other 49% gets reflected, scattered, or absorbed by the atmosphere.

-> Solar Radiation is also important for the Greenhouse effect (heat is trapped close to the surface of the earth) maintaining the surface warmth.

Explain how Solar Radiation and Latitude are related.

The amount of solar energy intercepted by the earth at any point varies with latitude.

*It decreases towards the poles (temperature/weather at the north and South Pole is very cold)

*It increases towards the equator (warmer temperature near the equator)

This variance in solar energy is due to the angle and the depth of the atmosphere (because the earth is curved, the farther we are from the equator, the more spread out the sun rays are: not as direct as it would be at the equator.)

What is Atmospheric Circulation and list the different types.

Definition: Movement of air in the atmosphere.

Uplift: warm air rises in the tropics

-> condenses into clouds + precipitates

-> cooling air forced North and South

Subsidence: cooling air from the tropics meet air moving Southward from the pole (both currents of air meet each other and are no longer 'excited')

-> areas where this occurs are often dry ex. Deserts

-> also occurs at the poles where air is dry (at 30 degrees North)

What are the Distinct Cell Formation?

The Distinct Cell Formation determines the general levels of precipitation.

Hadley Cell: 0-30 degrees -> Tropical

~ formed from the uplift at the equator

Polar Cell: 60-90 degrees -> Polar

~ formed from subsidence of air at the poles

Ferrel Cell: 30-60 degrees -> Temperate

~ Circulates air between and closes off the other cells

Drier at 30 and 90 degrees because of low energy air and subsidence. Wetter at 0 and 60 degrees because of uplift.

Wind Currents

Movement of air in the atmosphere.

Atmospheric circulation is linked to wind currents. If viewed from space wind would move directly north-south.

Corliolis Effect: apparent deflection of wind currents from Earth's perspective.

~ To the right in the Northern Hemisphere

~ To the left in the Southern Hemisphere

Ocean Currents

Movement of water in the oceans.

-> Global winds create ocean currents.

-> Continents act as obstructions to the water currents.

~ Currents in North Hemisphere: move clockwise.

~ Currents in South Hemisphere: move counter clockwise.

Warm Currents tend to move from the tropics outwards while cool currents originate from the polar regions (Ocean currents are the main thermal conveyors of the planet.)

What are the major influences that alter global temperature patterns and explain them.

1. Distribution of land and water~ Water is a better heat sink than land and retains heat longer~Type of vegetation on land influences heat uptake

-> Albedo: amount of solar radiation that a surface reflects

*Internal continental areas are less affected by the heating + cooling of ocean currents

*Precipitation tends to be higher in the SH relative to the NH b/c of uplift -> large surface area of water cover

-> Topography: mountains can create rain shadows

*deep continental areas become very dry due to long distance from water bodies

2. Elevation

~ Air temperature decreases with elevation ex. Snow peaked mountains

~ Warming effect of earths surface decrease with elevation

~ Increase air pressure at the surface causes molecules to move faster (molecules increase speed = warmer temperatures)

3. Earth's orbit around the Sun

~ The tilts of the Earth's axis results in seasonal temperature differences as it orbits around the sun

~ May to August: NH is tilted towards the sun (Increase in solar radiation results in summer)

~ Nov to Feb: NH is tilted away from the sun (decrease solar radiation results in winter)

*Seasons are reversed in the SH*

~ May to August: SH is tilted away from the sun = decrease solar radiation (winter)

~ Nov to Feb: SH is tilted towards the sun = increase radiation (summer)

~ Seasons restricted to temperate zones

~ Polar areas experience extreme day-night cycles (days where there's many hours of darkness)

~ Tropical areas experience a shift in the Intertropical Convergence Zone (ITCZ) and experience wet dry cycles

Environmental Heterogeneity: weather patterns differ at different spatial scales: Global -> Regional -> Local -> Micro

~ Global + regional climate patterns determine the large-scale distribution of plants and animals

~ Local climatic conditions do not match the general climate profiles of the larger region b/c local patterns of microclimate are the actual environmental conditions experienced by organism

Explain the properties of water and its importance.

Properties of Water: Water is a polar molecule that acts as a universal solvent -> should overtime allow for everything to dissolve

~ Water molecules become less dense (without this the whole lake would freeze) when moving from a liquid to a solid state

-> this property allows freshwater organisms to live below the surface of ice formed in the winter (frozen on top leaving warmer water below for the animals)

Importance of water

~ Aquatic ecosystems cover 75% of the planet making them the most dominant habitats

~ All living things contain between 75-95% water and most physiological processes depend on water

~ Almost all living phyla (groups of animal) of animals evolved in an aquatic environment which then evolved.

List and Explain the Properties of Water

Cohesion:

~ resists external forces that would break its bonds -> allows for less dense organisms to stay on top of the water

~ high surface tension caused by stronger attraction of water molecules to each other rather than air

Buoyancy:

~ when an object's specific density is lower than the fluid medium in which it sits, it will float to the surface

~ density = mass/volume

Viscosity:

~ a fluid medium's resistance to flow (fluid friction), water being forced downwards will exert pressure upwards (ex. Hand being forced down will result in water splashing up)

~ viscosity and buoyancy can operate together to force a moving object in the water closet to the surface -> swim in a way that it's pushing you back

~ comes from high cohesion of the water molecules

Explain the Microclimate variability of the Aquatic Environment.

Despite being the dominant habitat on Earth, the aquatic environment has. Low microclimate variability.

Divided by depth: mean ocean depth is 3.7 km (Max ~ 11 km)

~ the deeper you go, the more increased pressure it is

Divided by salinity: Saltwater (oceans - 97%), Freshwater (lakes, rivers, etc - 1%)

~ affected by evaporation + precipitation -> less evaporation in some areas due to high levels of precipitation ex: at 0 degrees and 60 degrees

~ freshwater environments are divided by pH rather than salinity

~ each unit of pH is a 10-fold increase in the concentration of H+

~ pH falls a scale from 0-14

-> 7 is neutral -> most organisms can only survive/live in neutral waters

-> below 7 is acidic (worse for most organisms)

-> above 7 is alkaline (basic) (tolerated by some organisms)

~ high solute concentration buffers the pH of water in the oceans

Explain the role of Light in Ecology and the Aquatic Environment.

75% of the ocean is 3-6 km deep -> the amount of light decreases raspidly after

*the less light there is, the colder it is

Solar Radiation is:

~ reflected back into the atmosphere

~ absorbed or reflected by suspended particles (alive + dead)

~ absorbed by water

~ declines exponentially with depth

~ distinct vertical profiles of light, temperature, oxygen, pressure, etc.

Direct Impact: plants

~ plants require sunlight for photosynthesis

~ restricted to top 100 m

Indirect Impact: animals

~ herbivores are restricted to depth where plants reside (about top 100 m)

~ animals inhabiting deep water (> 200 m) have adaptations:

* lack pigment

large eyes (for maximum light-gathering ability)

* organs that produce light (bioluminesence) ex. Anglerfish

* organisms undergo chemosynthesis in the ocean depths (taking geothermal energy + converting it into food energy)

Explain the relationship of Temperature in Ecology and the Aquatic Environment.

Exponential decline in solar radiation with depth -> decline in temperature with depth

Thermocline: region with most rapid decline in temperature -> as it approaches 4 - 0 degrees C

~ after temperature continues to decline with depth but at a slower rate

~ some form of thermal stratification occurs in all open bodies of water

~ mixing of the water column can break down this gradient (e.g wings, currents, seasonal)

~ seasonal variation in light leads to seasonal changes

~ permanent stratification occurs in the tropics, no mixing can take place

Fall turnover: the mixing of the thermal stratification of a water column due to the seasonal change of surface temperatures

~ water grows more dense as it cools to 4 degrees C

~ it grows less dense as it cools further from 4 - 0 degrees C

~ denser water sinks + less dense water floats to the surface (such that ice floats)

Explain the relationship of Oxygen in Ecology and the Aquatic Environment.

~ diffuses from the atmosphere into aquatic environments -> through a concentration gradient

~ produced by plants during photosynthesis

* restricts high concentrations of oxygen to surface waters

* limits respiration + metabolic activity of animals -> cellular respiration is limited

* mixing of the water column can break down this gradient

List Difficulties that an organism would face in an aquatic environment.

1. Access to light, oxygen and nutrients

2. Constant osmotic pressure

3. Low variability in microclimate

Explain how Life on Land (Terrestrial Environment) differs from Life in Water (Aquatic Environment.)

Life on Land

~ Like the aquatic environment, physical and chemical features impose constraints for life in the terrestrial environment

~ There is a high variability in microclimates compared to aquatic environments

-> variability of conditions especially in temperature and moisture ex. Rainforests vs desert

~ Water balance and desiccation (organisms on land must deal with significant loses of water due to evaporation

-> Living cells contain up to 95% water and must remain hydrated

-> Animals can drink or eat plants

-> Plants and microorganisms can obtain it directly from the soil or environment

~ Air has low density/viscosity relative to water; animals and plants subjected to large gravitational forces

-> cellulose/lignin reinforcing in plants (plants in water are more flexible b/c they are constantly passing water)

-> advanced skeletons in animals (plants buoyancy allows for plants to stay afloat)

However, it is soil (types of minerals + nutrients) upon which the foundation of all terrestrial life depends

Explain Soil and its applications in Ecology

~ Soil is hard to define. It is not just first, it is also composed of dead and decaying matter (recycling centre)

~ A natural product formed by the weathering of rocks and the actions of living organisms

~ composed of mineral and organic matter capable of supporting plant growth

~ More than just and abiotic medium for plant growth, it is a living system of interacting parts (biotic and abiotic)

~ Controls the fate of water in terrestrial ecosystems, breaks down waste products, releases nutrients + serves as a habitat for a community of

animals, fungi and microorganisms

~ Maintaining water balance is a major driver of evolution

Explain what Soil Depth is and its importance in Ecology.

Soil depths varies across the landscape: plants depend on this

~ Determined by degree of weathering, type of parent materials, and vegetation (organic matter additions)

-> Grasslands tend to have deep soils (root heavy = majority of plant is in the ground)

* Low decomposition rate and large amounts of organic materials being added from roots underground

-> Forest tend to have thin soils (above ground plant is the major part)

* High decomposition rate and organic material added on the surface (less nutrient rich soil)

-> Soils which develop on slopes tend to be shallow while those in alluvial plains tend to be deep (soils on a slop is not as deep as it is normally)

Explain what Soil Horizons is and its importance in Ecology.

~ Initially soil development occurs within the parent material

-> Overtime the soil changed from the surface down through the accumulation of organic material

-> Percolation of water downward moves material along with it (water leaking through cracks brings down the decaying organic matter)

~ Results in the formation of layers which are different physically, chemically and biologically

Layers: termed horizons, collectively called soil profile

-> 0 Horizon: the organic layer, it is made up of debris, in various stages of decomposition

-> A Horizon: often called the topsoil and is composed of both material and organic materials

-> B Horizon: often called the subsoil and contains less organic material and more mineral components relative to the A Horizon.

-> C Horizon: is the layer of unconsolidated material and is in general made of the same material from which the soil developed (pure mineral + clay ex. bedrock - contains very little organic matter)

Define Soil Types.

Differences in parent material, climate, topography, biota, site history and time yield different soil types with different minerals, nutrients and chemical properties

What causes variations in the moisture-holding capacity of soil?

1. Climate - directly influences the physical and chemical reactions in the soil + water availability

-> Temperature, precipitation, wind currents in exposed areas etc.

2. Type od Parent Material

-> Material from which the soil develops

-> Physical and chemical characteristics determine the properties of the soil

3. Topography: a sloped surface is less likely to hold moisture than flat ground due to gravitational forces

4. Aspect:

-> Windward facing slopes receive more precipitation

-> Differences in exposure to solar radiation and wind

5. Presence/absence + Type of Vegetation:

-> Vegetation alters microclimates

* light (via shading) shading from plants allow for more moist soil

* temperature (via shading)

* moisture (via use) actively taking water from the soil

* wind movement

* structure - habitat for animals

Microclimate Variability: vegetation provides a high diversity of microclimates (therefore many different animals) for terrestrial ecosystems)

Explain the Soil Property: Texture.

Texture is used to differentiate soil particle sizes. It is partially inherited from the type of parent material and the types of weathering processes

High degree of percolation (water leakage)

*Gravel > 2.0 mm

*Sand 0.05 - 2.0 mm

*Silt 0.002 - 0.05 mm

High moisture holding capacity

*Clay < 0.002 mm

~ A soils texture is a % of its sand, silt and clay components. Typically divided up into texture classes

~ Soil texture determines

*soil fertility

*the size of pore spaces

*large pores cause rapid water infiltration, percolation and drainage but have low holding capacity

*small pores cause slow water infiltration, percolation and drainage but the soil does have high holding capacity (hard to get water out of clay therefore plants can't get enough moisture from clay.

Explain the relationship between the individual and genetic information.

~ The individual is the reservoir of genetic information (individual cannot evolve)

~ An organisms cells contain identical strands of Deoxyribonucleic Acid (DNA) which is specific to the individual

Explain what DNA is and its components.

~ All DNA is composed of 4 different nucleotides arranged in an alpha helix (A, C, T, G)

G -> C, A -> T

~ DNA is contained on threadlike structures called chromosomes

~ Chromosomes come in matched pairs, one from each parent

~ DNA is organized into discrete subunits called genes -> codes for proteins

-> ex. Tay-Sachs Disease: the individual does not produce an enzyme (protein) called hexosaminidase A without which fatty tissue develops around nerve cells

Locus: particular location of a gene on a chromosome

Alleles: two or more alternative forms of a gene

-> results from slight differences in the DNA sequence of the gene

-> cause slight differences in form and function

Define Heterozygote

An individual that has different alleles at a particular locus on the pair of chromosomes (Aa)

~ When one allele is expressed over another it is dominant, and the allele that is not expressed is recessive (often recessive means it doesn't produce the protein)

Define Homozygous

An individual that has the same alleles at a particular locus on the pair of chromosomes

~ Dominant (AA)

~ Recessive (Aa)

Explain how the different alleles in Tay-Sachs Disease determine whether it is a homozygous or heterozygote.

A - codes for proper enzyme (protein)

a - does not code for protein

~ If AA, Aa -> individual is fine since atleast they have one good copy of the gene.

~ If aa -> individual would then have Tay-Sachs disease

Define Genotype

All the genetic characteristics of an individual (ie. Aa)

~ encoded in the DNA

~ fixed during the life time of an individual (but it doesn't mean that you'll look identical your whole life)

~ "set of genetic instructions"

Define Phenotype

Interaction of the genotype of an individual with its environment

~ outward expression of genes in the physiology, appearance and behaviour of an individual

~ responses of the individual to the environment may change (in some cases NOT FIXED during the lifetime of an individual)

Define Phenotypic Plasticity and explain how Phenotypic variation can be expressed.

Phenotypic plasticity is the ability of a genotype to alter its phenotypic expression under different environmental conditions.

Phenotypic variation can be expressed as:

1. Discrete, alternative forms

e.g. Social insects such as bees and ants

-> two types of larvae hatch with essentially the same genetic material

-> Queens - adults that produce

-> Soldiers/workers - adults that defend the other larvae

2. Continuous variations in form (continuously varying phenotypes)

-> Reaction norm = relationship between response of a continuously varying trait and environmental conditions

-> 1 genotype can result in many phenotypes

-> eg. Daphnia - respond (pigmentation) to varying UV radiation

* level of pigmentation varies continuously in response to UV radiation and predator abundance (high level of predation = transparent, low level of predation + high level of UV = bright colour/high pigmentation)

Explain what Mendelian Inheritance is and define genetic recombination.

Breeding of two individuals results in multiple combinations of alleles. It is how genetic variation is maintained.

~ 1 allele present on each chromosome of a parent

~ 1 chromosome (allele) is present in each gamete produced by a parent

~ gametes combine in offspring to form a new combination of alleles

Genetic recombination is all possible allele combinations from random mating of any combination of individuals in a population

The Individual vs. the Population

The individual: is the reservoir of genetic information; it is the unit of evolution.

The population: a group of individuals of the same species living together (where the effects of evolution are observed)

Explain the Hardy-Weinberg Principle and list its assumptions.

The genetic composition (allele frequencies) within a population does not change (evolution does not occur) unless one of the following

assumptions are broken:

1) Mutations: can create an allele

2) Migrations: results in addition or subtraction from the gene pool.

3) Small Population Size: with a smaller choice mating becomes less random and the gene pool is smaller

4) Non-Random Mating among individuals in a population (e.g. certain individuals more desirable)

• If random mating – allele frequencies will stay the same

5) Selection: evolution through natural selection

For the Hardy-Weinberg Principles you want: no mutations, no migration, large population size, random mating, no selection

Define Evolution

Evolution is a change in the genetic composition of a population of a species over time.

~ the match of individuals to their environment is a product of the successes and failures of their ancestors

~ the present form and function of individuals are specializations to their environment

Define Adaptation

Adaptation is the change in a genetically determined trait in response to environmental conditions that enhances the ability to cope with the environment

~ evolutionary process that takes place in a population over many generations through natural selection

Define Fitness

Fitness is the proportionate contribution of an individual to future generations

Involves:

~ Number of offspring produced (not just the offsprings but the offsprings of the offsprings and so on.)

~ Number of offspring surviving to reproductive age

Define Natural Selection and its Propeties.

Natural Selection operates on the individual

~ Natural section is the differential success of individuals though interactions with their environment and other organisms

-> Variation exists among individuals in a population in some inheritable trait

-> Variation results in differences in growth, survival and reproduction

~ Fitness is measured by the proportionate contribution an individual makes to future generations

~ In any given environment:

-> Traits which enable individuals to grow, survive and reproduce are passed on to future generations and selected for

-> Individuals without those traits are selected against

~ Selection pressures

-> Environmental conditions = abiotic factors

-> Species interactions (predators, competitors) = biotic factors

-> Selection pressures establish differences in fitness among individuals with different genotypes and phenotypes

-> Selected adaptations typically allow for optimal performance under a certain set of environmental conditions but these often limit its performance under another set

Underlying concept:

~ Individual variation has a genetic basis (traits are inherited)

~ Individuals with favourable traits are more likely to reproduce these individuals leave more descendants than others

-> Favourable traits are passed on to future generations at a higher frequency

~ Genetic composition of the population changes over generations or evolves

What Assumptions can be made regarding Evolution?

1. Individuals of a species are not identical – genetic variation

2. Some of this variation is heritable

3. Individuals leave different numbers of descendants – varying fitness

4. Fitness depends on the interaction between an individual’s traits and its abiotic & biotic environment

What is Speciation and what are the different types?

Biological Species Concept: distinguish species based on their potential to interbreed and produce fertile offspring

-> implies that reproductive isolation (or genetic isolation) defines a species because reproduction is the means of transferring genetic information (DNA)

Allopatric Speciation:

~ individuals are geographically isolated by a physical barrier (e.g. river, mountain, unsuitable habitat)

~ local environmental conditions will cause different selective pressures leading to divergence over time

Sympatric Speciation:

~ subpopulations are isolated without geographical isolation (e.g. timing of breeding, behavioural differences, sexual incompatabilty, etc.)

-> 1) Premating - prevent mating

*Separation of mating events in space and time

*Behaviour – e.g. mating songs of male birds (attract females)

*Mechanical or structural incompatibility

-> 2) Postmating - reduced survival or reproductive success of offspring

Plant Adaptations

Plants have evolved a variety of adaptations to successfully grow, reproduce and survive across the entire range of environmental conditions on Earth

Variations in:

- Light

- Temperature

- Water Availability

- Most ecosystems require the initial colonization of plants

Define Photosynthesis

Photosynthesis: process where energy from the sun is used to transform CO2 into carbohydrates (simple sugars) and O2

Where does Photosynthesis take place?

Photosynthesis takes place in specialized cells (mesophyll cells) in the leaf

What is the purpose of Chlorophyll in Photosynthesis?

Chlorophyll (light absorbing pigment) traps light energy → synthesizes ATP → this energy drives CO2 → O2 + sugars

*this chemical reaction is dependent on enzyme called rubisco

Define Cellular Respiration

Cellular respiration is the process by which organisms use oxygen to break down food molecules (carbohydrates) to get chemical energy (ATP) for cell functions, releasing carbon.

Where does Cellular Respiration occur?

In the mitochondria of cells (plant & animal) - carbohydrates are broken down to generate energy (ATP), releasing CO2.

Plants both use and produce CO2 and the difference in the rates of these two processes is:

• Net Photosynthesis = Photosynthesis (carbon uptake) – Respiration (carbon loss)

Define CO2 Acquisition

CO2 diffuses into the leaf through openings in the surface of the leaf, called stomata

~ As CO2 diffuses into the leaf, water diffuses out of the leaf (=transpiration) -> CO2 enters: atmosphere >> leaf

-> Water leaves: atmosphere << leaf

~ Water lost must be replaced with water taken by roots from the soil -> Plants must acquire essential resources: light, CO2, water, nutrients

How do plants acquire essential resources?

Leaf tissue - photosynthesis (uptake of CO2)

Stem tissue - structural support (gain access to light)

Root tissue - water and nutrient uptake from the soil

Explain the relationship between Plants and its different parts with Light.

Plants are either adapted to low light (shade-tolerant) or high light (shade-intolerant)

Tree Top (direct sunlight)

~ smaller, thicker leaves

→ reduces water loss in direct sunlight

Tree bottom (shade)

~ larger, thinner leaves

→ increases photosynthetic rate in shade

~ In many environments different leaf angles can be beneficial

-> Leaves in arid environments minimize evaporation by angling leaves away from the sun (greater reflection)

In shade, what limits photosynthesis?

In shade: photosynthesis is limited by availability of light ~Shade-tolerant (low light):

-> lower production of rubisco in leaf tissue (do not expend energy producing high amounts of rubisco)

How do plants especially shade-tolerant plants compensate for low light? Explain what the consequences/results of these adaptations are.

Lower maximum photosynthetic rate

Compensate by:

-> higher production of chlorophyll (light absorbing pigment)

-> higher leaf surface area

-> higher growth of leaves than roots

*increase the photosynthetic surface area to offset the decrease in photosynthetic rate (due to lower amount of rubisco)

Consequence:

Shade-intolerant - high growth rates under sunlight, but low rates in shade

Shade-tolerant - grow similarly under sunlight and shade cannot increase growth dramatically in sunlight because limited by rates of photosynthesis (lower concentration of rubisco)

Explain the adaptations of Mountain Avens (Dryas Integrifolia) to Light.

Mountain Avens are Shade-intolerant

~ Flowers track the movement if the sun

~ Parabolic formation of petals concentrate light to maintain a constant temperature of 25⁰C.

~ Keeps sex organs of the plant warm and creates a microhabitat favourable for pollinators

Explain the relationship between Plants and the Temperature.

Photosynthesis and respiration respond directly to variations in temperature

~ As temperatures rise above 0, rates of both respiration and photosynthesis increase

~ A maximum rate of photosynthesis and respiration occur at different points

~ Proteins denature and both processes stop eventually

~ To maintain optimal levels of photosynthesis a leaf must exchange excess heat with the surrounding environment

-> Heat loss by convection: transfer of heat to a moving fluid body (ie. Wind)

-> Heat loss by conduction (radiation): Heat moving from a warmer to a cooler body

-> Heat loss by evaporation (transpiration): Evaporation causes a loss of heat energy and temperatures drop due to evaporative cooling

What is Pubescence?

Small light-coloured hairs that line a leaf's surface and reflect light.

- Less heat obtained from solar radiation

- Also creates a insulative boundary later

What adaptation does the Skunk cabbage have to regulate its temperature?

Symplocarpus foetidus is an Endothermic plant.

~ Metabolically generates heat in the spring to thaw snow and attract pollinator

Plant VS. Temperature Adaptation: Accumulation of Compounds

The accumulation of sugars, amino acids (proline) and other solutes

-> Lowers the freezing point of water to prevent ice formation

Plant VS. Temperature Adaptation: Supercooling

Special anti freeze proteins preventing ice crystal growth allowing plants to survive up to -35C

-> Present in floral and shoot buds

Plant VS. Temperature Adaptation: Frost Hardening

Changes composition of membranes allowing cells to export water and ice to form between cells instead of within

-> Allows survival up to -50C

Plant VS. Temperature Adaptation: Deciduous Trees

~ Adaptive loss of leaves as the temperature drops in the fall months

~ Programmed death to survive the winter when the leaves would freeze

Plants and their relationship with Water Availability.

~ Plants have evolved a range of adaptations in response to the variability of precipitation and soil moisture

~ When the atmospheric humidity and soil moisture levels are low plants will close their stomata

-> Can also occur on a daily basis, where mid day, stomata close to conserve water

-> Remain open during the mornings and later afternoon

Short time Scales (Regulatory)

~ Regulate opening and closing of stomata during different parts of the day

e.g. close stomata during hottest part of the day when highest water loss through evaporation

~ Leaf curling or wilting - reduces the surface area of the leaf exposed to solar radiation and, thus, water loss

Moderate time Scales (Acclimatory/Developmental)

Individuals can balance leaf vs root tissue

Wet conditions (ideal): ↑ leaf tissue & ↓ root and shoot I

-> Increase the photosynthetic surface (maximizes CO2 uptake and photosynthetic rates → growth)

-> No increase in other tissues (i.e. shoot, root) because this increases the rate of respiration (CO2 loss)

Dry conditions: ↑ root tissue & ↓ leaf and shoot

-> Increases the volume of tissue in the soil to extract water

-> Reduces the surface area of leaf tissue to reduce water loss

Long time Scales (evolution)

Leaf morphology adaptations to dry conditions:

*smaller and thicker leaves (water storage)

*smaller stomata

*cover leaves in wax, resin, little hairs (e.g. cactus)

Some species have alternative photosynthetic pathways. More efficient photosynthesis reduces water loss:

*C4 photosynthesis: 3% of plants, common in grasses

*CAM photosynthesis: 7% of plants, common in epiphytes and cacti

*Add an extra step in the conversion of CO2 into an organic acid before entering Calvin cycle (dark reactions)

Environmental Change

Organisms live in constantly changing environments

• Many temporal scales: daily, seasonally, annually

• Fitness depends on an individual's ability to cope with environmental change

• To maximize fitness - an individual's response to these changes must be shorter

than the period of change

What are the 3 Individual Responses to environmental change and explain them in detail.

1. Developmental (years)

• Individual alters its development to produce a phenotype most suitable to

a persistent slow change in environmental conditions

e.g. Wing length in European freshwater Water Striders (Gerris spp.) – inhabiting temporary

ponds

- Eggs hatch (spring)

- Adult lifespan is short (reproduce & die during one summer)

- 2 morphs (discrete phenotypes)

Long winged - can fly, move if pond dries up, more energy into survival than reproduction

Short-winged - cannot fly, cannot move if pond dries up, more energy into reproduction than survival

2. Acclimatory (days – weeks)

• Changes in response to seasonal variations

e.g. thickening of fur for winter (fur and feathers create an insulative boundary layer)

= habituation (becoming used to something) of an organism’s physiological response to environmental conditions

• Tolerances are not fixed but are preconditioned by recent experience with

environmental conditions

E.g.

Insect:

"Freeze avoidance strategy”

• as temperatures start to decrease in fall

• convert glycogen reserves → alcohol

• alcohol – depress the freezing point of the body → freeze avoidance

Wood frog (Rana sylvatica): Freeze Tolerance

• Similar to frost hardening in plants

• Expels fluid interior of cells and controls the ice nucleation (the initial process that occurs in the formation of a crystal from a solution, a liquid, or a vapor) process in intercellular space

• Can survive temps up to -50⁰C

Tardigrades or "water bears": Dessication Tolerance

• allow their tissues to dry up when there is no available water

• revitalized when water again becomes available

• not a permanent solution

3. Regulatory (seconds – minutes)

• Rapid changes in behaviour or rates of physiological processes

e.g. shivering in animals

How do animals regulate their temperature in response to environmental change?

(1) Conformers – allow internal conditions to follow external changes

Poikilothermy (Conforming) – cannot maintain constant body temperature (body temp varies)

• Most amphibians, fish and insects

• Most aquatic organisms

• Only active in a narrow range of temperatures

(2) Regulators – maintain constant internal conditions

Homeothermy (Regulating) – maintain constant body temperature (homeostasis)

• most birds and mammals ~ 36 – 41 degrees C (temp. at which biochemical

processes within cells are efficient)

• Highly active under varying temperatures

What are the different ways in which organisms can regulate body temperature within a certain range? What are their advantages and disadvantages?

Ectotherms - regulate body temperature by gaining heat from external sources

(Poikilotherm)

-> Adv. - energy expenditure can be low

-> Disadv. – growth, reproduction and survival is limited by temperature

fluctuations (Active only in a narrow range of temps)

Endotherms - regulate body temperature by the production of heat (metabolism)

(Homeotherm)

-> Adv. – growth, reproduction & survival is not as affected by temperature

fluctuations

*Constant performance of biochemical reactions at a range of

environmental temperatures

*Active at a wide range of temperatures

-> Disadv. - energy expenditure must be high to maintain metabolic heat

production

~ Most ectotherms are poikilotherms (i.e. body temps vary)

~ Most endotherms are homeotherms (i.e. constant temp)

Define Homeostasis

Homeostasis = ability to maintain constant internal conditions in a varying

environment. Organisms must maintain an equilibrium between their internal and external environments (Cells, organs and enzymatic processes function with a certain set of limits (range)

-> Always involves a negative feedback system

I. mechanism that senses the internal condition

II. means of comparing the actual with the desired

internal condition

III. apparatus that alters the internal condition in

preferred direction

What are Limitations of Ectotherms?

~ Must behaviourally generate heat

~ Ectotherms generate heat when active

-> Every aspect of ecology and behaviour is influenced by the need to regulate body

temperature

What are Limitations of Endotherms?

~ Endotherm’s ability to maintain constant body temperature is limited under low

temperatures:

• Short-term – by physiological capacity to generate heat

• Long-term – by ability to gather food (or energy) to satisfy requirements for

metabolic heat production

• animals usually starve to death before they die of direct causes of cold

temperatures

• Reduce energetic costs by altering the loss/gain of heat from environment in a

number of ways…

*Become larger!*

• body size is one of the most important animal characteristics

• body size dictates the morphology, ecology, physiology and evolution of an

organism

• the importance of body size in energy conservation lies in the surface area to

volume ratio…(Allometry)

Define Allometry and describe its relationship with Surface Area to Volume Ration.

Allometric relationship = a relative increase in a physical or physiological property of an organism in

relation to its body size

-> As body size ↑,

V ↑ faster than SA

-> As body size changes,

SA/V ratio changes

-> As SA/V ratio changes,

Heat loss to environment changes

• Body heat is produced through metabolic processes (endotherms)

• The larger the V, the greater the total amount of heat required to keep warm

... but less heat is lost through the outer surface of the organism

• Heat gain must be greater than heat loss

Small organisms and their SA/V ratio

• High SA/V

• Require less heat but hard to keep warm!

Large organisms and their SA/V ratio

• Low SA/V

• Require more heat but it is retained easier

What is Bergmann's Rule?

A broadly distributed group of species tend to be larger in size in

colder environments and smaller in warmer environment

• On a single species scale think of the white-tailed deer example

• On a multi-species scale this rule often breaks down